It's a nice article, but reading it I can really understand why their body language is so confusing to people at first!
I just had a bit of a laugh, for example different levels of a lowered head and fluff configurations could mean "I love you, scritch me," "I'm afraid, go away," "I'm angry, touch me and die," and "I'm aiming my flight." It's completely true but the "subtitles" that are really obvious to people who've had their birds for a while go completely unnoticed by others.
Really it's no wonder why people can't tell what their new bird is thinking for a couple weeks.
The only thing I can think to add that I've found interesting, 90% of the people I've spoken to with a tame lovebird say their birds vibrate (Wing and Body Quivering in the article) when very happy, excited, or feeling especially cuddly. It's entirely different from fear or cold, the rest of their body language is a clear give away. Other species will do this too I've been told, but it's apparently very common in lovies.
Sometimes Peanut vibrates so hard when super excited (like I've just surprised her with a serving of millet) she'll nearly fall off the dish.
